• Journal of Electrical Engineering and Technology
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• 제12권3호
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• pp.1195-1202
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• 2017

Induction motors often reach their maximum efficiency at the nominal load. In most applications, the machine load is not equal to the nominal load, thus reduces the motor efficiency and turns a greater percent of power into loss. In this paper, the induction motor control problem has been investigated to reduce the system losses. The Field Oriented Control method (FOC) has been employed in this paper. In this research, the mathematical equations related to system losses are calculated in relation to torque and speed, and then the q- and d-axis are summarized according to the current components. After that, the proposed method is applied along with d- and q-axis. In the recent three decades, many techniques have been suggested to improve the induction motor performance using smart and non-smart methods. In this paper, a new PSO-Fuzzy method have used in real time. The fuzzy logic method serves as speed controller in q-axis and PSO algorithm controls the optimum flux in d-axis. It will be proved that the use of this combined method will lead to a significant improvement in motor efficiency.

• Steel and Composite Structures
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• 제24권6호
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• pp.711-726
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• 2017

In the present work, by considering the agglomeration effect of single-walled carbon nanotubes, free vibration characteristics of functionally graded (FG) nanocomposite sandwich plates resting on Pasternak foundation are presented. The volume fractions of randomly oriented agglomerated single-walled carbon nanotubes (SWCNTs) are assumed to be graded in the thickness direction. To determine the effect of CNT agglomeration on the elastic properties of CNT-reinforced composites, a two-parameter micromechanical model of agglomeration is employed. In this research work, an equivalent continuum model based on the Eshelby-Mori-Tanaka approach is employed to estimate the effective constitutive law of the elastic isotropic medium (matrix) with oriented straight CNTs. The 2-D generalized differential quadrature method (GDQM) as an efficient and accurate numerical tool is used to discretize the equations of motion and to implement the various boundary conditions. The proposed rectangular plates have two opposite edges simply supported, while all possible combinations of free, simply supported and clamped boundary conditions are applied to the other two edges. The benefit of using the considered power-law distribution is to illustrate and present useful results arising from symmetric and asymmetric profiles. The effects of two-parameter elastic foundation modulus, geometrical and material parameters together with the boundary conditions on the frequency parameters of the laminated FG nanocomposite plates are investigated. It is shown that the natural frequencies of structure are seriously affected by the influence of CNTs agglomeration. This study serves as a benchmark for assessing the validity of numerical methods or two-dimensional theories used to analysis of laminated plates.

• Steel and Composite Structures
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• 제25권6호
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• pp.649-661
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• 2017

This paper is motivated by the lack of studies in the technical literature concerning to the influence of carbon nanotubes (CNTs) waviness and aspect ratio on the vibrational behavior of functionally graded nanocomposite annular sector plates resting on two-parameter elastic foundations. The carbon nanotube-reinforced (CNTR) plate has smooth variation of CNT fraction based on the power-law distribution in the thickness direction, and the material properties are also estimated by the extended rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. Parametric studies are carried out to highlight the influence of CNTs volume fraction, waviness and aspect ratio, boundary conditions and elastic foundation on vibrational behavior of FG-CNT thick sectorial plates. The study is carried out based on three-dimensional theory of elasticity and in contrary to two-dimensional theories, such as classical, the first- and the higher-order shear deformation plate theories, this approach does not neglect transverse normal deformations. The annular sector plate is assumed to be simply supported in the radial edges while any arbitrary boundary conditions are applied to the other two circular edges including simply supported, clamped and free. For an overall comprehension on 3-D vibration of annular sector plates, some mode shape contour plots are reported in this research work.

• Steel and Composite Structures
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• 제39권3호
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• pp.275-290
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• 2021

The main purpose of this research work is to investigate the critical buckling load of functionally graded (FG) porous plates with graphene platelets (GPLs) reinforcement using generalized differential quadrature (GDQ) method at thermal condition. It is supposed that the GPL nanofillers and the porosity coefficient vary continuously along the plate thickness direction. Generally, the thermal distribution is considered to be nonlinear and the temperature changing continuously through the thickness of the nanocomposite plates according to the power-law distribution. To model closed cell FG porous material reinforced with GPLs, Halpin-Tsai micromechanical modeling in conjunction with Gaussian-Random field scheme are used, through which mechanical properties of the structures can be extracted. Based on the third order shear deformation theory (TSDT) and the Hamilton's principle, the equations of motion are established and solved for various boundary conditions (B.Cs). The fast rate of convergence and accuracy of the method are investigated through the different solved examples and validity of the present study is evaluated by comparing its numerical results with those available in the literature. A special attention is drawn to the role of GPLs weight fraction, GPLs patterns through the thickness, porosity coefficient and distribution of porosity on critical buckling load. Results reveal that the importance of thermal condition on of the critical load of FGP-GPL reinforced nanocomposite plates.

• 중국학논총
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• 제27호
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• pp.147-166
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• 2009

New year pictures prevailed from 1660s to 1860. Especially, the reign period of Emperor Qianlong(r. 1736-1795) was the period of prosperity. The period of 1660s when new year pictures were started to be popular was the reign period of Emperor Kangxi(r. 1662-1722) was just started and corresponded to Emperor Kangxi's promulgation of "Sacred Edict." Chinese operas such as Peking opera were very popular among common people in the period from 1660s to 1860 when new year pictures prevailed. Qing emperors as foreign ruler chose the way of ruling their people by means of cultural influence in stead of military power. However their culture effort was not efficient toward the majority of illiterate people. New year pictures offered every information about the world through visual icons to the illiterate people at that time who perceived the world by means of seeing. They met the world through visual information offered by new year pictures. New year pictures were the stronger visual medium to spread and educate "Sacred Edict" to illiterate subjects than any other guide books published by elite officers.

• 영어영문학
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• 제58권1호
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• pp.3-19
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• 2012

This paper argues that the hard-boiled detective fiction is not a commercialized imitation of the classical detective novels but a revisionist detective fiction. Producing a radically different type of detectives from the traditional ones, the hard-boiled detective fiction provides a new, opposing paradigm of criminality, class, and masculinity to the classical detective fiction. Classical detective novels, through the heroic portrayal of high-class detectives capturing and punishing lower-class criminals, reassure class hierarchy. Hard-boiled detective novels, however, representing the ruling classes as the root of social oppression and political corruption, define the power elite as criminals. Whereas the classical detective fiction displays aristocratic masculinity, the hard-boiled detective fiction embodies working-class masculinity. The classical detective is generally represented as a genteel dilettante solving the mysteries of crimes, in his leisure time, through logical reasoning and scientific techniques. The hard-boiled detective, however, solves crimes by using violence and earns his living from catching criminals. The hard-boiled detective also maintains an absolute independence by keeping a distance from all forms of authority and connection. The representation of hard-boiled detective as a tough, rebellious, independent guy can be interpreted as a reaction to the advent of corporate capitalism and the rise of labor control in the 1920s.

• 한국조경학회지
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• 제49권5호
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• pp.27-45
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• 2021

본 연구는 서울 근대화의 주역인 김현옥 서울시장이 추진한 공원녹지 정책의 경로를 추적하고 그 특성을 밝히는 것을 목적으로 하였다. 그의 공원녹지 정책 논의를 발전시키기 위해 하이 모더니즘의 관점을 투영하였다. 하이 모더니즘은 전후 도시재건사업에서 나타나는 불가피한 현상으로 국가 엘리트들에 의한 이상적 사회질서와 합리적 계획에 대한 신념의 형태로 출현하였다. 이것의 특징은 가독성 구축, 권력에 의한 신속성과 편의성, 민간 참여와 이익 창출, 그리고 건설되는 도시의 스펙타클을 실현하는 것이었다. 하이 모더니스트로서 김현옥 서울시장의 도시계획은 폭증하는 인구와 서울 영토의 확장에서 비롯되었다. 그리고 그의 공원녹지 정책은 서울 외곽으로 공원을 확장시켰고, 도심에 위치한 공원을 전용하는 이원적 태도를 보였다. 한편 공원조성을 위해 민간의 참여를 유도하였지만 장소성을 소거하고, 관련 제도를 배제하는 근대화의 이면을 보여 주었다. 김현옥 시장의 공원녹지 정책의 경로는 인구증가에 대응하고 공원의 잠식을 해소하는 것에서 출발하였다. 그리고 정책의 궁극적 목표는 도시계획 현실화를 수용하고 비재정방식 실험하는 것이었다. 하이 모더니즘을 반영한 그의 공원녹지 정책의 특성은 첫째, 국토계획학회, HURPI 그리고 장문기로 대표하는 엘리트들이 참여하였고, 둘째, 사방위의 축, 표고 기준 그리고 인구 예측을 반영한 합리적 계획에 의한 공원녹지의 가독성을 구축하였다. 셋째, 급격한 도시변화에 대응하기 위해 신속하게 공원을 해제하였고 넷째, 민간자본을 유치하기 위한 이벤트와 스펙타클을 과시하였다.

• 한국운동역학회지
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• 제16권3호
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• pp.53-63
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• 2006

The general objective of this study was to investigate biomechanical characteristics of bowling swing using three-dimensional cinematography. This study focused specifically on movements of the upper body segments during a bowling swing. Eight elite female bowling players participated in this study. Subjects performed bowling swing and their performance was sampled at 60 frame/sec using two high-speed video cameras with a synchronizer. After digitizing images from two cameras, the two-dimensional coordinates were used to produce three-dimensional coordinates of the 12 body segments (20 joint reference makers). The obtained three-dimensional coordinates were fed to a custom-written kinematic and kinetic analyses program (LabView 6.1, National Instrument, Austin, TX, USA). The analyses determined the linear and angular kinematic variables of the body segments with which joint force and torque of the lower and upper trunks and the shoulder were estimated based on the Newton-Euler equations. It was found that during the bowling swing the peak linear velocities of the body segments were reached in sequence the trunk, the shoulder, the elbow, the wrist, and the bowl. This result indicates that linear momentum of the lower body and the trunk transmits to the arm segment during the bowling swing. The joint torques of the torso and the arm occurred almost simultaneously, indicating that bowling swing seem to be a push-like motion, rather than a proximal-distal sequence motion in which many of throwing motions are categorized. The ultimate objective of the bowling swing is to release a heavy-weight bowl with power and consistency. Therefore, the bowling swing observed in this study well agrees with that bowlers use the stepping to increase the linear velocity of the bowl, the simple pendulum system and the push-like segmental motion in the torso and the arm segment to enhance the power at the release of the bowl.

• 대한안전경영과학회지
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• 제12권1호
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• pp.51-57
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• 2010

Cycling that transform human energy into mechanical energy is one of the man-machine systems out of sports fields. Benchmarking means "improving ourselves by learning from others', therefore benchmarking toward dominant cyclist is necessary on field. The goals of this study were to provide important factors on multi-disciplines (kinematics, physiology, power, psychology) for a tailored-training program that is suitable to individual characteristics. Two cyclists participated in this study and gave consent to the experimental procedure. One was dominant cyclist (years: 21 yrs, height: 177 cm, mass: 70 kg), and the other was non-dominant cyclist (years: 21, height: 176, mass: 70). Kinematic data were recorded using six infrared cameras (240Hz) and QTM (software). Physiological data (VO2max, AT) were acquired according to graded exercising test with cycle ergometer and power with Wingate test used by Bar-Or et. al (1977) and to evaluate muscle function with Cybex. Psychological data were collected with competitive state anxiety inventory (CSAI-2) that was devised by Martens et. al (1990) and athletes' self-management questionnaire (ASMQ) of Huh (2003). It appears that the dominant's CV of ankle joint angle was higher than non-dominant's CV and dominant's pedaling pattern was consistent in biomechanics domain, which the dominant's values for all factors ware higher than non-dominant's values in physical, and physiological domain, and their values between cognitive anxiety and somatic anxiety were contrary to each other in psychology. Further research on multi-disciplines may lead to the development of tailored-optimal training programs applicable with key factors to enhance athletic performance by means of research including athlete, coach and parents.

• 한국운동역학회지
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• 제22권4호
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• pp.413-419
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• 2012

The purpose of this study was to investigate the effects of increased saddle height on the length and activity pattern of vastus lateralis (VL) and biceps femoris (BF) muscle. To compare the effects of increased saddle height, Preferred (self-selected height of subject) and High saddle height (approximately 5% higher saddle height than self-selected) were used. Seven elite cyclists (career: $16.1{\pm}8.5years$) participated in 3 min. sub-maximal pedaling tests under the same cadence (90 RPM) and pedaling power (150 W). Hip and knee joint angles, and the length and activity of VL and BF were compared by measuring 3D motion and electromyography (EMG) data. Results showed that there were significant differences in peak extension timing of the hip joint angle and the range of motion of the hip and knee joint between different saddle heights. Although there were significant differences in muscle length of both muscles with increasing saddle height, the timing and amount of muscle activity differed only at the BF. These findings suggest that the timing and amount of bi-articular muscle activity (i.e. BF) can be altered by changing the saddle height. For practically applying these results, further study is necessary to evaluate the effects of various cadence and the pedaling power with various saddle heights.